1. Area of the Art
The invention relates generally to fluid-moving devices. More particularly, the invention is directed to fluid-moving devices, such as piston pumps, with integrated valves.
2. Description of the Related Art
In many types of fluid-moving equipment, such as liquid pumps, slurry pumps, dry mixers, dispensers and numerous other devices, the pumping action is accomplished by a sliding plunger, rod, piston, or another similar member, reciprocally moving inside a stationary bearing. Typically, a pump housing encases the bearing and the piston, while the input/output valves are set outside of the pump housing. Most commonly, connecting tubing and fittings are utilized to connect the valves to the pump. As the fluid passes through each connection, pump to fitting, fitting to tubing, etc., the fluid flow is disturbed and the accuracy and precision of the fluid-moving equipment are adversely affected. Also, depending on the selected tubing type and operating pressure, the tubing may flex and bend, thus disrupting the fluid flow even more and further affecting the dispensing accuracy of the fluid-moving equipment.
Automated analytical instruments are broadly used in chemical, biological, and clinical laboratories, often for testing small sample volumes. When dealing with small volumes or diluted samples, even a minute change in sample dispensing accuracy may lead to substantial analytical errors. When conventional pumps are utilized for sample dispensing in an analytical instrument, the tubing and the fittings between the pump and the input/output valves require frequent maintenance checks for leaks and flow obstructions in order to provide a reliable operation of the instrument. Also, the worn-out tubing and fittings have to be replaced promptly.
Therefore, the conventional fluid-moving equipment does not provide a consistent and accurate fluid dispensing, unless the connecting fittings and tubing are adjusted or replaced frequently. Consequently, the maintenance of the conventional fluid-moving equipment is laborious and costly, particularly when the equipment is used for processing large sample batches, diluted samples, or small sample volumes.
Accordingly, it is an objective of the present invention to provide a fluid-moving device which avoids the undesirable features of the prior devices. Particularly, it is an objective of the present invention to provide a convenient fluid-moving device with high dispensing accuracy, relatively low maintenance cost, and superior reliability in use.
These and other objects are achieved in a fluid-moving device of the present invention. The device includes a housing defining a suction chamber and at least one internal passageway formed inside the housing. A first end of the internal passageway opens to the suction chamber and a second end of the internal passageway connects to an outside surface of the housing. The fluid-moving device of the present invention also includes a pumping structure disposed inside the suction chamber for generating a pressure inside the suction chamber.
The fluid-moving device of the present invention may be connected to or integrated with a secondary device or structure by utilizing passageways formed in the housing instead of conventional tubing. In a preferred embodiment, the secondary device is a valve with at least one fluid communication port. The fluid communication port of the valve is connected to the second end of the internal passageway, whereby the pressure generated in the suction chamber is communicated to the valve.
The valve may be mounted on the housing. Alternatively, a valve chamber may be provided in the housing and the valve may be positioned in the valve chamber, at least partially. The fluid-moving device of the present invention may also include valve passageways formed inside the housing. The valve passageways provide a fluid communication between fluid communication ports of the valve and the outside. In one embodiment, a manifold is utilized as an intermediate element for connecting the valve passageways to fluid supplies and fluid sinks. The manifold has a casing, at least one input port, at least one output port, and a plurality of manifold passageways formed in the manifold casing. The manifold passageways connect the valve passageways to the manifold input and output ports.
In another aspect, the invention provides a method of making a fluid-moving device with an integrated valve. The method comprises:
(a) providing a solid housing having a suction chamber; and
(b) forming an internal passageway, wherein a first end of the internal passageway opens to the suction chamber and a second end of the internal passageway connects to an outside surface of the housing.
By eliminating tubing and connectors between the valve and the pumping structure, the present fluid-moving device alleviates many of the problems associated with the conventional devices discussed above. The advantages of this approach include a greater precision of fluid-delivery, simplified assembly and maintenance, significantly improved reliability, and a decreased maintenance cost. The device is well-suited for use in any system that requires drawing, moving, and dispensing of fluids.
The invention may be particularly advantageous for use in conjunction with analytical instrumentation that requires precise dispensing of liquid samples. For example, a piston pump with an integrated valve manufactured in accordance with the present invention may be beneficially utilized for sample aspiration and dispensing in NexGen Access System (Beckman Instruments, CA), disclosed in a commonly assigned U.S. patent application titled xe2x80x9cMethod and System for Automated Immunochemistry Analysisxe2x80x9d, concurrently filed with the present application, which is incorporated by reference herein in its entirety.
The invention is defined in its fullest scope in the appended claims and is described below in its preferred embodiments.